The objective of this grant is to develop statistical methods useful for epidemiologic cohort and case-control studies of both chronic and infectious diseases. The focus will be on the development of statistical methods for (1) case-control studies with dependent data; (2) genetic studies with binary traits; (3) cohort studies with partial information on causes and/or dates of death and (4) case- control studies with prevalent cases. The above four different types of studies share one thing in common, namely, at least one of the following two assumptions is violated. They are (i) the observed data are assumed to be independent of each other and (ii) the disease status, especially the cause and the date of occurrence, are assumed to be clearly identified. In this grant, for each one of four studies, we will (A) point out the place and the extent to which the existing statistical method breaks down, (b) develop new methods appropriate for the study and (C) apply the methods to the data set for which this work was motivated from.